Recently, it was reported that in the bronchoalveolar lavage fluid, proinflammatory FCN+ monocyte-derived macrophages were significantly increased and FABP4+ alveolar macrophages (AMs) were greatly reduced in the patients with severe COVID-19, whereas mild and moderate cases were characterized by the presence of highly clonally expanded CD8+ T cells6. Here, FABP4 is linked to COVID-19.